METHOD FOR DETERMINING THE STATE OF CHARGE OF NICKEL CADMIUM BATTERIES BY MEASURING THE FARAD CAPACITANCE THEREOF

• US 3,562,634 A
• Filed: 12/16/1968
• Issued: 02/09/1971
• Est. Priority Date: 12/16/1968
• Status: Expired due to Term

• Current Assignee: Norman Latner
• Original Assignee: Norman Latner
• Inventors: Latner, Norman
• Time in patent office: 785 Days
• US Class Current: 324/427
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01R 31/378 specially adapted for the type of battery or accumulator

Abstract

Method for predicting the capacity of nickel-cadmium batteries with a standard reference curve that indicates battery capacitance as a function of the state-of-charge of a given nickel-cadmium battery type wherein the standard reference curve is used with the measurement of the capacitance of any battery of the given type to indicate the state-of-charge of the battery.

Claims

2. The method of claim 1 for determining the state-of-charge of a nickel-cadmium battery wherein the batteries are initially discharged, fully charged, left standing for three hours, and then the farad capacitance thereof is measured whereby the measured capacitance indicates the state-of-charge of the battery with reference to the standard reference curve.

3. The method of claim 2 in which said initial discharging is down to 1.1 volts at a ten hour rate and is followed by charging that breaks down oxide on the cadmium electrode of said battery.

4. Method for measuring the capacity of nickel-cadmium batteries whose terminal voltage remains constant over a relatively wide range of charge, comprising the steps of nondestructively measuring the farad capacitance of said nickel-cadmium batteries substantially independently of contact and internal battery resistance and selectively determining from said capacitance measurement the state-of-chargE of said batteries without discharging the same.

5. The method claim 4 in which said measured farad capacitance is a function of the state-of-charge of said batteries corresponding to the curve of FIG. 3 for the use of said batteries as remote energy sources for balloon flights.

6. The method of claim 4 wherein said measured farad capacitance corresponds to the relationship of the farad capacitance to the state-of-charge of nickel-cadmium batteries of a single type selected from the group, consisting of button, cylindrical and button stack nickel-cadmium batteries, and said measurement of said farad capacitance is selectively made with batteries of that type.

7. The method of claim 4 wherein said farad capacitance of said batteries is measured with a 60 Hz four lead, transformer ratio arm bridge for measuring said capacitance substantially independently of the contact and internal resistance of said batteries.